The present invention relates to a process for the manufacture of dimethicone copolyol compounds, which are free of odor and consequently suitable for use in personal care products. The process is one in which water is added to the dimethicone copolyol being treated, hydrolyzing susceptible groups off the compound and azeotropically distilling off the odor bodies.
Certain types of non-hydrolyzable siloxane-polyether copolymers are well known in the art and are readily available through many suppliers. These materials are called dimethicone copoylol compounds. These compounds are manufactured by the co-reaction of poly(dimethyl-siloxanes) containing SiH groups (hydrosiloxanes) with olefinic polyethers wherein the olefinic sites are allyl groups. The general reaction whereby these non-hydrolyzable linkages are created between silicone and polyether groups is: 
However, the above reaction is not the sole reaction that is taking place during the preparation of the copolymer. It has been established that a significant percentage of the allyl groups are isomerized under the addition reaction conditions to give propenyl polyethers, which do not participate in the hydrosilation reaction. See, for example, U.S. Pat. No. 5,869,727 to Crane et al issued February 1999.
It has become common practice in the industry to use stoichiometric excesses (20 mole % or more) of the allyl polyethers to insure reaction of all the SiH groups. The excess unreacted allyl polyether or isomerized propenyl polyether are thus present as inert diluents, thereby reducing the potency or active concentration of the final copolymer.
Another competing undesirable reaction is that some of the SiH groups react with sources of hydroxy containing contaminants, or solvents containing hydroxy functionality such as water, methanol or ethanol. These convert the SiH sites to SiOR sites acts to reduce the number of incorporated polyether moieties and it is known that the hydrogen gas released from this undesirable side reaction can be catalytically added across the double bond of the polyether. These groups break down giving odor. This latent odor source causes problems with odor stability over time.
Another source of concern is the HCl that is liberated when using hexachloroplatinic acid. It was clearly demonstrated by a group of French investigators that the hexachloroplatinic acid will liberate HCl as a by-product in the reaction system. This by-product is suspected to have a deleterious effect on the reaction system (for example, by inducing parallel protodesilylation reaction at the xe2x80x94Cxe2x80x94Sixe2x80x94 main chain bonds). This is shown by G. deMarignan, D. Teysse, S. Boileau, J. Malthete and C. Noel, Polymer, 29, 1318 (1988).
Several approached have been taken to reduce the presence of odor bodies in the dimethicone copolyol. U.S. Pat. No. 5,869,727 to Crane et al issued February 1999, incorporated herein by reference, attempts to remove the odor by running the hydrosilylation under a vacuum of 1-750 mmHg. This approach provides only minimal relief in that it does not address the hydrolysis of the competing Sixe2x80x94OR compounds addressed above, and does not take advantage of azeotropic distillation as a vehicle to remove the odor bodies.
Another approach has been used in U.S. Pat. No. 6,162,888 to Lee et all, incorporated herein by reference. The Lee invention relates to a method of making a silicone polyether comprising (I) reacting a mixture comprising an olefin functional polyether, an organohydrogensiloxane, and a homogeneous transition metal hydrosilylation catalyst, and (II) subjecting the product of (I) to hydrogen gas. The method of this invention reduces the amount of olefinic species present, which are precursors to odorous compounds. This approach has several drawbacks. While the hydrogenation does lower the amount of vinyl groups present, the resulting saturated compound has very little difference in boiling point and is not an improvement in odor. 
A third approach covered in U.S. Pat. No. 5,696,192 to Harashima deals with conducting a hydrosilylation reaction in an organic solvent between (A) a polyoxyalkylene bearing alkenyl at a single terminal and having a peroxide value not exceeding 3 meq/kg, and a total content of aldehyde plus ketone not exceeding 100 ppm by weight; (B) an organohydrogenpolysiloxane that contains at least one silicon-bonded hydrogen atom in the molecule; in the presence of (C) a platinum catalyst. A water treatment is then given but the amount of water is equivalent to at least one weight percent of the total amount of components (A) and (B); and the water is removed under reduced pressure.
We have surprisingly found that the incorporation of between 5 and 10% water followed by a boiling of the water at atmospheric conditions, up to a temperature of between 110 and 150 effectively controls the odor without the need for controlling the ketone level,, or the other steps outlined by Harashima. It has been surprisingly been found that the removal of water at atmospheric conditions, not under vacuum, and at elevated temperatures, rather than reduced temperatures facilitates the azeotropic distillation of the odor bodies from the dimethicone copolyol.
The present invention provides a simple effective and non-destructive method to eliminate the odor that is undesirable in the dimethicone copolyol compounds produced by the hydrosilation reaction. We have surprisingly found a process that effectively removes odor when applied to dimethicone copolyol compounds that have been prepared by hydrosilylation reactions known in the art. The process to deodorize dimethicone copolyol compounds relies upon the ability of water to hydrolyse odor-releasing compounds (principally Sixe2x80x94OR compounds) and to remove the volatile odor causing materials present in the dimethicone copolyol when the water is distilled off as the dimethicone copolyol is heated to between 110xc2x0 and 150xc2x0 C.
The present invention makes use of the heretofore unappreciated facts that (1) water added to the finished dimethicone copolyol and allowed to mix for a period of time hydrolyses the Sixe2x80x94OR compounds that are made as a consequence of the hydrosilylation reaction, liberating all at once the odorous compounds that are removed in with water by distillation, (2) that only when elevated temperature is used to boil off the water and odorous materials is the odor successfully removed. Removing water under lower temperatures and reduced pressure simple does not allow for the ability to distill off odorous materials.
The present invention therefore is a process to deodorize dimethicone copolyol compounds conforming to the following structure: 
wherein;
a is an integer ranging from 0 to 2,000;
b is an integer ranging from 1 to 20;
c is an integer ranging from 0 to 20;
x, y and z are independently integers ranging from 0 to 20;
n is an integer ranging from 3 to 31;
which comprises;
(a) add between 5 and 20 % by weight of water to said dimethicone copolyol;
(b) mix the resulting mixture for between 10-30 minutes;
(c) heat the reaction mixture to between 120xc2x0 and 150xc2x0 C. under atmospheric conditions;
removing the distillate.
This procedure has been found to be very effective in providing products that are odor free for extended periods of time, and consequently f much interest to the personal care industry.